The FBI by mid-January will activate a nationwide facial recognition service in select states that will allow local police to identify unknown subjects in photos, bureau officials told Nextgov.

The federal government is embarking on a multiyear, $1 billion dollar overhaul of the FBI’s existing fingerprint database to more quickly and accurately identify suspects, partly through applying other biometric markers, such as iris scans and voice recordings.

Often law enforcement authorities will “have a photo of a person and for whatever reason they just don’t know who it is [but they know] this is clearly the missing link to our case,” said Nick Megna, a unit chief at the FBI’s criminal justice information services division. The new facial recognition service can help provide that missing link by retrieving a list of mug shots ranked in order of similarity to the features of the subject in the photo.